Switch devices



NOV. 22, 1960 TER 2,961,502

SWITCH DEVICES Original Filed Nov. 18, 194s IN V EN TOR.

F RFINK H. HESTER BY 68 [A rme/vr/ SWITCH DEVICES Frank A. Hester, NewYork, N.Y., assignor, by mesne assignments, to the United States ofAmerica as. represented by the Secretaryof the Navy Original applicationNov. 18, 1943, Ser. No. 510,798. Divided and this application Dec. 23,1944, Ser. No. 569,521

8 Claims. (Cl. ZOO-61.01)

This invention relates to switch devices, and. more particularly to anelectric switch for opening and closing.

closed andclaimed in my above identified copending application. Undercertain circumstances, it is desirable to avoid firing of the charge,and the primary object of my present invention is to provide an improvedelectric switch for use in a depth charge firing control circuit whichwill accomplish this purpose.

More part cularly, it is an object of my present invention to provide anelectric switch of the inertia type which is responsive to mechanicalvibrations, such as acoustical waves or the like, for controlling anelectric circuit in which it may be connected.

Another object of my present invention is to provide an improvedelectric switch as aforesaid which can be made very sensitive.

Still another object of my present invention is to provide an improvedinertia type, electric circuit controlling switch which will serve toinstantaneously open or close a circuit upon predetermined movement of avibratory member thereof.

A further obiect of my present invention is to provide an inertia type.electric circuit control switch as above set forth which is particularlyuseful in a depth charge detonating control circuit for controlling thefiring of the charge.

It is also an ob ect of my present invention to provide an inertia type,electric circuit controlling switch as above set forth which is very smple in construction, inexpensive in cost. and highly efiicient in use.

In accordance with my present invention, I provide a pair of vibratoryspring members, preferably but not necessarilv of the leaf spring type,one of which is relatively stiff and the other of which is relative yflexible. One end of the stiff spring is secured to a suitable supportand its other end is freely suspended. Secured to the stiff spring, inproximity to its freely suspended end, is a weight or mass which istuned with this spring to some suitable, predetermined frequency; orflexible spring has one end secured to the aforesaid weight or mass andits other end is also freely suspended for cooperation with a contactmember which may be carried by the aforementioned weight or may besecured to some other suitable member in spaced relation to the freelysuspended, vibratory end of the more flexible spring. The latter springis tuned, either by itself or with a suitably added mass or weight, tosubstan tially the same frequency as that to which the stifi Spring andits associated mass are tuned. The relative The second fiexibilities ofthe two springs are such that,- when the stiif spring is. set into.vibration by an external force to vibrate with some particular amplitudeat substantial- 1y its resonant frequency, the second or flexible springwill be causedv to vibrate thereby at substantially the same frequencybut with much greater amplitude. Upon vibration of the latter spring,which constitutes one contact element of the switch, it will engage theothercontact element of the switch to thereby complete the electriccircuit in which it is connected. The last mentioned contact element maybe made adjustable relative to the flexible spring so that the circuitwill not be closed until the vibration of the flexible spring hasreached a certain, desired amplitude. In this way, the switch may bemade extremely sensitive.

The novel features that I consider characteristic of my invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and method of operation, aswell as additional objects and advantages thereof, will best beunderstood from the following description of one embodiment thereof,when read in connection with the accompanying drawingin which the singlefigure shows a central, sectional view of a switch constructed inaccordance with my present invention and connected in the controlcircuit of a depth charge firing device.

Referring more particularly to the drawing, there is shown a depthcharge detonating control device 1 comprising a diaphragm of magneticmaterial having a vibratory, central portion 5 coupled to the outer,annular portion thereof by a thin, flexible, annular portion 7 wherebythe central portion 5 is capable of acting substantially as a piston. Amagnetostriotive rod or the like 9 is secured to the vibratory portion 5of the diaphragm and forms therewith a vibratory system. The rod 9 hastwo motional nodes around one of which is placed a winding 11 whichconstitutes a driving coil for the vibratory diaphragm portion 5, andaround the other of which is a winding 13 constituting a driven coil.The driving coil or winding 11 is connected in the output or patecircuit of a power amplifier 15 (eg, a type 3A4 tube), and the drivencoil 13 is connected in the input or grid circuit of a combined detectorand amplifier 17 (e.g., a type 1T4 tube). The vibratory diaphragmportion 5, the magnetostrictive rod 9, the two windings 11 and 13, andthe tubes 15 and 17 form an oscillating circuit which generates theoutgoing signal. The output of the detector-amplifier i7 is connected tothe power amplifier l5 and excites the power ampifier 15 which thendrives the rod 9 through its output coil 11, while the rod 9, in turn,excites the detector-amplifier tube 17 through the receiving coil 13.This oscillatory system is arranged to oscillate preferably at thenatural frequency of the vibratory system comprised of the diaphragmportion 5 and the rod 9, and this frequency may be approximately 25 kc.per second. The length of the rod 9 is preferably equal to three-fourthsof the wave length at the natural frequency of the oscillating. system,and, as stated above, the windings 11 and 13 are preferably arrangedabout the rod 9 at the two motional nodes thereof.

An oscillatory system as above described may be connected to a depthcharge in the manner more fully disclosed in my above identifiedcopending application and makes use of the Doppler effect to obtainfiring of the charge at the point of closest approach to the target. Asthe depth charge falls, the unit emits, continuously, a high frequencyacoustic signal which is reflected from the target back to the diaphragm3.. Due to the fact that a relative velocity exists between the depthcharge -and;the

target, the received, reflected signal and the outgoing,

transmitted signal and on the magnitude of the relative velocity betweenthe charge and the target. The weak, reflected signal is'received by thevibratory-portion 50f the diaphragm and sets into vibration themagnetostrictive rod 9. This energizes the driven coil 13, and thesignal is amplified by regeneration around the oscillator loop. Due tothis regeneration, the amplitude of the signal is suflicient to producea heterodyne at the grid of the detector-amplifier 17. Thus, a componentof which the frequency is the difference between the outgoing signal andthe reflected signal appears in the output of the detectoramplifier 17,since this tube acts as a simple, grid-leak detector. The circuit is sodesigned that the detectoramplifier 17 operates at maximum detectorsensitivity, while the power amplifier 15 operates at maximum poweroutput.

' The output of the amplifier 17 is connected to a multistage, selectiveamplifier 19 which responds only to very low frequencies. When thefrequency difference is in the order of about 30 cycles per second (oranyother suit able, low frequency), this signal is passed by theamplifier 19 and is applied to a limiter amplifier 21. Thecharacteristic of this circuit, as more particularly described in myabove identified copending application, is such that it will not respondat all to weak signals, while its response to strongsignals isindependent of the signal strength.

The output of the limiter amplifier 21 is coupled to a normally-blocked,cold-cathode discharge device 23 (e.g., a type 359A tube), which acts asa firing tube. A capacitor 25 is connected in series with the tube 23,as is also a detonator 27 of a suitable depth charge. The capacitor 25is normally charged through a resistor 29 from a suitable DC voltagesource connected at the point A. When a strong signal is applied to thelimiter amplifier 21 for predetermined time (e.g., one-fifth second). itwill effect firing of the tube 23. When the tube 23 is fired, itprovides a current discharge path therethrough for the capacitor 25 andthe detonator 27 whereby firing of the charge is effected.

Under certain circumstances, it is desirable to prevent firing of thecharge as, for example, in response to certain extraneous noises such asthose produced by the explosion of another charge in the vicinity of thecontrolled charge. For this purpose, I provide a switch 31 constructedin accordance with my present invention and adapted to act as ananti-countermine switch. The switch 31 includes a relatively stiff leafspring 33 which is connected at one end to the diaphragm 3 or to someother suitable member rigidly connected with the diaphragm, the oppositeend of the spring 33 being freely suspended.

37 and 39 remain spaced from each other. Any abnormally intense,undesirable acoustical waves having cornponent frequencies of the orderof the resonant frequency of the switch 31 which strike the diaphragm 3will cause the spring 33 and the mass 35 to vibrate at the resonantfrequency thereof. This, in turn, will cause the spring 37 to vibrate atsubstantially this resonant frequency, but with much greater amplitude,to contact the screw 39 and thereby complete a circuit through aresistor 45 connected to the capacitor 25 in shunt relation with thedischarge tube 23 and the detonator 27. Thus, when an abnormally intensewave strikes the diaphragm 3, the circuit I through the resistor 45 iscompleted before the one through the discharge tube 23 is completed andthe capacitor 25 discharges through the resistor 45 instead of throughthe detonator 27. In this way, prematurefiring of the depth charge isavoided. If the source of the abnormally intense waves or undesiredvibrations should be at a considerable distance. fro-m the controlleddepth charge, the amplitude of the abnormal vibrations striking thediaphragm 3 may be very small. It is for this reason that the switch 31is arranged as above described so as to greatly multiply the amplitudeof vibrations in the spring 37 due to the relative flexibility of thesprings 33 and 37 and thereby insure engagement of the spring 37 withthe terminal screw 39 to complete the alternative current discharge paththrough the resistor 45 for the capacitor 25. By making the screw 39adjustable on the terminal plate 41, the spacing between the contactelements 37 and 39 can be varied to require a greater or lesseramplitude of vibration of the spring 37 before it will contact the screw39. In this way, the sensitivity of the switch 31 can be readilycontrolled.

Although I have shown and described but a single form of my presentinvention, it will undoubtedly be apparent to those skilled in the artthat many other modifications thereof, as well as changes in theparticular one described, are possible. For example, instead ofemploying leaf springs, other suitable vibratory members To the latterend of the spring 33 is connected a weight n is in connection withsafes.

may be used, or other forms of springs may be used, if desired. Also,while I have described my present invention with particular reference toa firing control circuit of a depth charge, it should be apparent tothose skilled in the art that many other uses thereof are possible. Forexample, the switch of my present invention may be employed in a controlcircuit for a vibratory system which is not to exceed a certain degreeof vibration. In

such case, the switch will close when the spring 37 has attained apredetermined amplitude of vibration to thereby control the vibratingforce in any suitable manner. Another possible use of the switch of mypresent invention The switch may, for example, be mounted in somesuitable location within the safe and set into vibration when anunauthorized person readily suggest themselves.

vide the desired tuning. The diaphragm 3 may be grounded and the spring33, the mass 35, and the spring 37 are conductively connected thereto.As clearly shown in the drawing, the spring 37 also has one end freelysuspended and arranged to serve as one contact element of the switch forcooperation with a second contact element 39. The contact element 39 maycomprise an adjustable screw carried by a terminal plate 41 which may bemounted either on the mass 35 through an insulating block 43 or on someother, suitable member which is insulated from the contact spring 37.

Upon normal operation of the firing circuit as described above, theswitch 31 is inactive and the contact elements tampers with the safe, asby tapping, whereupon the switch will be operated to close an alarmcircuit or the like. Many other uses and applications will, no doubt, Itherefore desire that my invention shall not be limited except insofaras is made necessary by the prior art and by the spirit of the appendedclaims.

I claim 'as my invention:

1. An inertia switch device comprising a first vibra-' tory member, asecond vibratory member carried by said first vibratory member andconstituting one contact element of said switch, and a second contactelement cooperatively associated with said second vibratory memher inspaced relation thereto, said vibratory members being so related to eachother that upon vibration of said first vibratory member with relativelysmall amplitude, said second vibratory member will be caused to vibratethereby with relatively large amplitude and will engage said secondcontact element for closing said switch.

2. An inertia switch device comprising a first vibra;

tory member tuned to a predetermined frequency, a second vibratorymember carried by said first named vibratory member and constituting onecontact element of said switch, said second vibratory member being tunedto substantially the same frequency as said first vibratory member, anda second contact element cooperatively associated with said secondvibratory member in spaced relation thereto, said vibratory membersbeing so related to each other that upon vibration of said firstvibratory member at said frequency with relatively small amplitude, saidsecond vibratory member will be caused to vibrate thereby atsubstantially said frequency with relatively large amplitude and willengage said second contact element for closing said switch.

3. An inertia switch device comprising a first spring member, a massassociated therewith and tuned with said spring member to apredetermined frequency, a second spring member resiliently carried bysaid mass and constituting one contact element of said switch, and asecond contact element cooperatively associated with said second springmember in spaced relation thereto, said spring members being so relatedto each other that upon vibration of said first spring member at saidfrequency with relatively small amplitude, said second spring memberwill be caused to vibrate thereby at substantially said frequency withrelatively large amplitude and will engage said second contact elementfor closing said switch.

4. An inertia switch device comprising a first spring member, a massassociated therewith and tuned with said spring member to apredetermined frequency, a second spring member resiliently carried bysaid mass and constituting one contact element of said switch, and meansalso carried by said mass constituting a second contact element of saidswitch, said second spring member being so related to said mass and saidfirst spring member that upon vibration of said first spring member andsaid mass at said frequency with relatively small amplitude, said secondspring member will be caused to vibrate thereby at substantially saidfrequency with relatively large amplitude and will engage said secondcontact element for closing said switch.

5. An inertia switch device comprising a first and relatively stiffspring member, a mass associated therewith and tuned with said springmember to a predetermined frequency, a second and relatively flexiblespring member resiliently carried by said mass and constituting onecontact element of said switch, and means also carried by said massconstituting a second contact element of said switch, said second springmember being so related to said mass and said first spring member thatupon vibration of said first spring member at said frequency withrelatively small amplitude, said second spring member will be caused tovibrate at said frequency with relatively large amplitude and willengage said second contact element for closing said switch.

6. An inertia switch device according to claim 3 Wherein the mass andresilience of said second spring member are such that second springmember is also resonant at substantially said predetermined frequency.

7. An inertia switch device comprising a first and relatively stiff leafspring fixed at one end and freely suspended at its other end, a masscarried by said spring in proximity to its said free end, said mass andspring being tuned to a predetermined frequency, a second and relativelyflexible leaf spring having one end fixedly connected to said mass andits other end freely suspended relative to said mass, said second springbeing also tuned to substantially said predetermined frequency and itsfreely suspended end constituting one contact element of said switch,and a second switch contact element carried by said mass in associationwith the freely suspended end of said second leaf spring, said leafsprings being so related that upon vibration of said first spring withrelatively small amplitude at said frequency, said second spring will becaused to vibrate thereby at substantially said frequency with greateramplitude whereby its freely suspended end will be brought intoengagement with said second contact member for closing said switch.

8. An inertia switch device according to claim 7 wherein said secondswitch contact element is adjustably carried by said mass for adjustmentrelative to said second leaf spring.

No references cited.

